As Euro Arrives, Only a Few Coins
Are Worth Collecting, Experts Say

When a young man recently visited Michel Prieur's shop in Paris and offered to sell a 900-year-old silver coin with a medieval cross on its face, the veteran numismatist could hardly believe his luck.

The coin was struck in 1101 as a tribute to King Philippe the First of France, who bought the town of Dun-le-Roi from a count fleeing France to fight in the Crusades. Barely battered after nine generations, the coin was in fine...